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Vegetation, phytomass and carbon storage in Northern Eurasia during the last glacial–interglacial cycle and the Holocene
Chemical Geology 159 Ž1999. 191–204
Vegetation, phytomass and carbon storage in Northern Eurasia during the last glacial–interglacial cycle and the Holocene A.A. Velichko ) , E.M. Zelikson, O.K. Borisova Laboratory of EÕolutionary Geography, Institute of Geography RAS, Staromonetny, 29 Moscow, Russian Federation Received 7 April 1998; received in revised form 10 September 1998; accepted 27 November 1998
Abstract The phytomass Žthe biomass of terrestrial vegetation. is one of the main reservoirs of carbon, as carbon makes up approximately 0.45 of the phytomass by weight wAjtay, G.L., Ketner, P., Duvigneaud, P., 1979. Terrestrial primary production and phytomass. In: Bolin, B., Degens, E.T., Kempe, S., Ketner, P. ŽEds.., The Global Carbon Cycle, SCOPE 13, Wiley, Chichester, pp. 123–181.x. During the glacial–interglacial climatic rhythm both composition and geographical distribution of vegetation over Northern Eurasia have been repeatedly subjected to major changes, accompanied by corresponding changes of phytomass and carbon storage. Of special interest are three key intervals within the last 125,000 years: the Mikulino ŽEem. Interglacial optimum, about 125 ka BP; the Last Glacial maximum, 18–20 ka BP and the Holocene optimum, 5.5–6 ka BP. These intervals correspond to the extreme states of the environment. Vegetation which existed in Northern Eurasia 125, 18–20 and 5.5–6 ka BP, accumulated 377.1 Gt, 66.1 Gt and 292.1 Gt of phytomass, which corresponds to 169.7 Gt, 29.9 Gt and 131.4 Gt of carbon, respectively. Compared to present-day carbon storage in the phytomass of potential vegetation Žtaken as 100%., these values are 155%, 27% and 120%, respectively. q 1999 Elsevier Science B.V. All rights reserved. Keywords: Vegetation; Phytomass; Carbon
1. Introduction The phytomass of terrestrial vegetation is one of the main reservoirs of carbon storage. Carbon makes up about 45% of the phytomass by weight ŽAjtay et al., 1979.. During the last glacial–interglacial climatic cycle vegetation cover was subjected to major changes. As a result, the phytomass and carbon storage also changed. Phytomass and carbon storage
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in terrestrial vegetation are reconstructed for four periods of time, corresponding to different values of global heat supply: Ž1. for the mean global temperature 18C higher than the present-day one Žthe climatic optimum of the Holocene.; Ž2. for the maximum cooling of the Last Ice Age, when the mean global temperature was 3–48C lower than at present; Ž3. for the mean global temperature approximately 28C higher than the present-day one Žthe optimum of the last, Mikulinos Eem Interglacial.; Ž4. for the present-day climatic conditions Žmodern carbon storage in terrestrial phytomass has been calculated for potential Žreconstructed. vegetation..
0009-2541r99r$ - see front matter q 1999 Elsevier Science B.V. All rights reserved. PII: S 0 0 0 9 - 2 5 4 1 Ž 9 9 . 0 0 0 2 9 - 7
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A.A. Velichko et al.r Chemical Geology 159 (1999) 191–204
2. Methods Estimations of phytomass storage are mainly achieved by modelling, or by reconstruction of the spatial distribution of terrestrial biomes of high taxonomic rank ŽAdams et al., 1990.. This article is based on more detailed reconstruction of the vegetation cover, taking into account palynological Žin some cases also palaeocarpological. data, as well as ecology of modern plants and plant communities. The only source of information on specific values of phytomass and carbon storage in the vegetation of the past is from modern plant communities, which can be considered their closest analogues. The specific values for specific plant communities and especially for communities formed by the same dominant species in different climatic and landscape conditions vary in a broad range, depending on the floristic composition of plant communities, the canopy density in the forest, the density of herbaceous cover, the number of storeys in plant communities. These features depend in their turn on the composition of species, on climatic and soil conditions, and other characteristics of the environment. For example, the mean specific value of phytomass storage ŽSVPS. for the broad-leaved forest of the Russian Plain reaches 22 ktrkm2 in the area between the Oka and Don Rivers, 33 ktrkm2 between Pripyat’ and Middle Dnieper, and up to 40 ktrkm2 between the Dniestr and Danube valleys ŽBazilevich, 1993.. Thus, an important methodological question is how and by which criteria we should choose an analogue for a reconstruction of the phytomass storage. The quantitative correlation of components in pollen spectra obtained from the sediments of certain ages correspond to the type of vegetation that existed during the time interval under study and the composition of its dominants. Pollen analysis enables us to distinguish the dominants of certain plant communities at the taxonomic rank of genera for arboreal plants, or families for herbaceous plants. For reconstruction of vegetation, paleofloristic data are especially informative as some of the plant species are closely connected with the communities of a definite type Žso-called indicative plants.. If such species are identified in a fossil flora, one can reconstruct ancient plant communities using modern ecological
demands and coenotic connections of indicative plants. Bazilevich Ž1993. estimated SVPS for the modern plant communities in the territory of the former Soviet Union. The monograph contains SVPS for the main vegetation types within the FSU territory Žmore than 2500 estimations.. We used these estimations to calculate the phytomass and carbon storage in the vegetation of the Northern Eurasia for the above mentioned key intervals of the past and for the modern potential vegetation. The SVPS for the modern zonal vegetation types were calculated as mean values of all the estimations for given vegetation type within the area, published by Bazilevich. For example, this author gave SVPS for different types of the middle taiga spruce forests for three regions of East Europe Žwhich were based on primary data on 18 key-sites.. The phytomass storage is 220.50 trha, 227.57 trha and 236.55 trha in western, central and eastern parts of the subzone, respectively; the mean value is 228 trha, or 22.8 ktrkm2 . For southern taiga subzone of the East European spruce forest, the same author gives three regional specific values Ž227.77 trha, 291.38 trha, 359.89 trha. calculated on the basis of 38 key-sites. The mean value for the southern taiga is 311.35 trha Žapproximately 31.1 ktrkm2 .. SVPS for complex types of vegetation were calculated using similar procedure. According to Bazilevich Ž1993., the phytomass storage of oak forest within the forest-steppe zone is 293.7 trha Žthe mean value is derived from measurements from 39 key-sites., that of linden forest is 192.8 trha Ž3 key-sites.. Thus, the mean value for forest vegetation in the forest-steppe zone is 243,3 trha. The specific phytomass storage in the meadow steppe vegetation was estimated for three regions by 18 key-sites as 12.7 trha, 16.5 trha and 10.6 trha, the mean value being 13.30 trha. It is supposed that in the foreststeppe, under natural Žpre-agricultural. conditions, the woodland occupied about one half of the area ŽRastitel’nost’ Evropeiskoi chasti SSSR, 1980.. In that case, the mean specific value of the phytomass storage for the forest-steppe zone can be calculated simply as Ž243.26 q 13.30.: 2 s 128.28 trha Ž12.8 ktrkm2 ..
A.A. Velichko et al.r Chemical Geology 159 (1999) 191–204
Similarly, the SVPS can be estimated for the forest-tundra. At present, woods occupy 2% to 3% of the area in the north of the subzone and 20% to 30% in its southern part ŽAlekhin, 1951.. The rest of the area is covered by tundra and marsh vegetation. According to Bazilevich Ž1993., marsh communities are very close to tundra by SVPS. To choose modern analogues to the vegetation types of the Mikulino ŽEemian. and Valdai ŽLast Glacial maximum. plant communities, one has to use various approaches, depending upon availability of paleofloristic data. It is especially difficult to estimate SVPS for the periglacial steppes and foreststeppes, which occupied vast areas in Eurasia during glacial epochs, because such communities have no complete analogue in the present-day vegetation. If the paleofloristic data available are sufficient, we can use a method of modern concentration area of plant species of the fossil flora, that is the region where the majority of plant species—components of certain fossil flora—grow at present ŽGrichuk, 1979.. It was shown that modern vegetation of such a region represents the closest analogue of the one existed at the site during the studied time interval. For example, the SVPS for the spruce and birch forest with broad-leaved trees, spread over the northern part of the East Europe during the Mikulino optimum Žunit 6 on the map., was estimated by the following procedure. The composition of species typical for such forest in Mikulino Interglacial can be found at present in the territory adjacent to Fennish and Riga Gulfs of the Baltic Sea. The estimations of the SVPS for modern forests within the area, based on 11 key-sites, are published by Bazilevich: 220.50 and 247.16 trha, the mean of these values is 233.83 trha Žapproximately 23.4 ktrkm2 .. With the use of the method, modern plant communities closest to the periglacial steppe of the central East Europe at the maximum of the Valdai Glacial were identified: those of the dry steppe in the cold and continental Altai region Žabout 6 trha, Kuminova, 1960.. 1
1
We accepted here the value of 0.7 ktrkm2 , taking into consideration the presence of arboreal plant communities with higher SVPS in the periglacial steppe vegetation, though such communities occupied only a small part of the area.
193
If the paleofloristic data available are insufficient to apply the method of the modern concentration regions, one can take into consideration specific features of the past vegetation, indicated by the presence of characteristic plants in the fossil flora. One can suppose that such estimations based on the floristic indications are less reliable than those calculated by SVPS in the regions of maximum modern concentration of the plant species—components of the fossil flora. But usually the estimations attained by the two methods are similar, for example, the SVPS characteristic for the modern analogues of the periglacial steppe found by floristic indicators Ždry and salt steppes in East Europe. are also close to 6 trha Ž6.50, 5.76 and 5.70 trha, according to Bazilevich.. A similar approach was used in the case when present-day plant communities in the region of concentration of the fossil flora do not correspond to those of the past vegetation. For example, the closest modern floristic analogue to the broad-leaved forest with hornbeam, that occupied a major part of East Europe during the Mikulino Interglacial, can be found in the Upper Elba River catchment basin. It means, that at present, the majority of plant species, which grew in the central region of the East European Plain during the Mikulino Interglacial, can be found in the area. As the broad-leaved forests with hornbeam at the Elba River basin occupy places with the most fertile soil Žbroadly used for agriculture for a long time. they are considerably disturbed, so that their modern SVPS cannot be used for reconstruction. Instead, the specific values of the other broad-leaved forest with similar composition of dominant trees and coenotic structure were used for calculations of the phytomass storage in the floristically rich broadleaved forest of the Mikulino Interglacial optimum. The vegetation maps compiled by Khotinski for the Holocene optimum and by Grichuk for the Valdai Glacial maximum and the Mikulino Interglacial optimum ŽVelichko, in print. were used to calculate areas occupied by various vegetation types. All the maps were based on abundant palynological data: information on 290, 285 and about 400 sites was used to compile the vegetation maps of the Mikulino Interglacial optimum, Valdai Glacial maximum and the Holocene optimum, respectively. First drafts of these maps were published in the monograph Late
194
A.A. Velichko et al.r Chemical Geology 159 (1999) 191–204
Quaternary environments of the Soviet Union ŽVelichko, 1984., where the methods of vegetation reconstruction, used by above mentioned authors, were described. To estimate the phytomass and carbon storage in the modern potential vegetation, the map by Sochava et al. Ž1964. was used Ždisturbances of the vegetation due to agricultural and industrial activities were not taken into consideration.. All the four maps were simplified by merging the areas of plant communities with similar features and phytomass storage indexes. 3. Results The total phytomass storage in the modern potential Õegetation in the Northern Eurasia within the FSU boundaries amounts to 248.1 Gt, implying a carbon content of 111.6 Gt. The bulk of the storage is made up by dark coniferous and larch forest, the two most widespread formations within the area ŽFig. 1 and Table 1.. The vegetation formations that spread over the East Europe at the second half of the Atlantic period of the Holocene Ž5.5–6.0 ka BP., were close to their modern analogues. But due to the warmer climate, their ranges, and especially their northern boundaries, were different from the present-day ones ŽFig. 2.. According to the reconstruction of vegetation made by Khotinski, the zonal structure of vegetation at the Holocene optimum was similar to that of today. In the north of Eurasia the tundra zone was considerably narrower than at present. The forest tundra reached the seashore in the north of the Kola Peninsula. It was also spread over the southern parts of the Yamal and Taimyr Peninsulas. Only in the northeast of Eurasia was the northern tree line close to the present-day one. The area of the forest zone was considerably greater than today, especially that of dark coniferous forest. Coniferous-broad-leaved forest in the East Europe occupied the present-day area of the southern taiga subzone, while the northern limit of the broad-leaved forest was close to the modern one, or somewhat shifted to the north. On the whole, at the Holocene optimum an area of the nemoral broad-leaved forest exceeded the present one, while that of the forest steppe was smaller than now. In West Siberia, the herb–grass steppe occupied a larger area than at present. Comparison be-
tween the modern vegetation map and that of the Holocene optimum shows that at the Holocene optimum, the areas of plant formations with high values of the phytomass storage were greater than today due to increased heat and moisture supply. Therefore, total phytomass and carbon storage in the Northern Eurasia exceeded the modern values. The phytomass storage reached 292.1 Gt, that of carbon being 131.4 Gt, or 120% of the modern potential value ŽTable 2.. Plant communities that spread over Northern Eurasia during the Maximum cooling of the Last Glacial epoch, 18–20 ka BP, differed from the modern ones by their structure and other features. According to the reconstruction of vegetation made by Grichuk, the major part of the area was occupied by communities of periglacial tundra Žin the north. and periglacial steppe types ŽFig. 3.. The tree species least demanding to the environmental conditions, such as birch, pine, larch, and spruce, formed small woodland patches within the periglacial tundra and steppe zones. The boreal forest did not exist in East Europe, but survived in the southern part of Siberia and in the Far East, in relatively mild conditions of mountain regions. Due to a severe climate of the ice age, the forest belt there was narrow and discontinuous, the woodlands being very open with low quality of tree stands. Consequently, the phytomass and carbon storage in such forests was low. An area occupied by the vegetation of nemoral type has been even more reduced. Small patches of the broad-leaved forest during the ice age were confined to Crimea, Caucasus, Southern Urals, and southern part of the Far East. The total phytomass and carbon storage in the scanty vegetation of the ice age was drastically reduced compared to the one characteristic for the interglacial epochs ŽTable 3.. For the stage of maximum cooling of the Last Glacial, they amounted to 27% of the modern values: the phytomass storage did not exceed 66.1 Gt, that of carbon, 29.9 Gt. At the Mikulino Interglacial optimum, the northern boundary of the forest zone in the European Russia shifted 200–300 km to the north compared to its present-day position, so that the forest reached the coast of the Arctic Ocean ŽFig. 4.. In Siberia, the tree line shifted towards north of the modern one by 450–550 km. The area of tundra was then far smaller
A.A. Velichko et al.r Chemical Geology 159 (1999) 191–204
Fig. 1. Modern vegetation of the Northern Eurasia Žin the borders of FSU.. According to Sochava et al. Ž1964., simplified. Explanation: see Table 1. 195
196
A.A. Velichko et al.r Chemical Geology 159 (1999) 191–204
Table 1 Phytomass and carbon storage in the present-day potential vegetation in the Northern Eurasia Žin the borders of FSU. Vegetation
Area in thousand km2
Phytomass storage Specific values, Total ktrkm2 t = 10 9
1. Arctic desert 2. Tundra 3a. Birch forest-tundra 3c. Larch forest-tundra 4a. Northern taiga spruce forest 4b. Middle taiga spruce forest 4c. Southern taiga spruce forest 5. Siberian pine and spruce middle taiga forest 6. Siberian pine–spruce–fir and spruce–fir southern taiga forest 7. Mountain dark coniferous forest 9. Birch forest 10. Beringian birch forest in Kamchatka 12. Larch forest 13. Larch–pine forest 14. Larch–pine and pine light forest with steppe-like field layer 15. Siberian dwarf–pine elfin wood 16. Pine swamp forest 17. Coniferous-broad-leaved forest 18a. Broad-leaved-coniferous Far East forest 18b. Pine-broad-leaved Crimean forest 19. Broad-leaved Žoak, elm. lime. forest 20. Broad-leaved Far East forest 21. Meadow steppe combined with broad-leaved forest 22. Meadow steppe combined with birch forest 23. Meadow steppe combined with pine, birch and larch forest 24. Herb–grass steppe 25a. Grass xerophytic steppe 25b. Mountain steppe 26. Grass–sagebrush steppe Žsemidesert. 27. Desert 28. Tugai Žriverine complex with forest, bushes and meadows in Middle Asian river valeys. and oases 29. Mountain tundra combined with shrubs Total
101 1362 105 230 488 640 626 687 540 551 253 110 6380 39 37 165 536 711 88 18 579 103 380 351 68 850 1087 38 623 2143 37
0.1 1.3 1.6 3.1 16.7 22.8 31.1 20.5 25.8 22.8 21.3 11.2 13.2 24.2 17.4 6.8 21.4 26.3 31.4 20.5 32.5 23.6 13.0 6.5 7.4 1.5 1.0 1.9 0.7 1.2 9.2
- 0.1 1.8 0.2 0.7 8.1 14.6 19.5 14.1 13.9 12.5 5.4 1.2 84.2 0.9 0.6 1.1 11.5 18.7 2.7 0.3 18.8 2.4 4.9 2.3 0.5 1.3 1,1 0.1 0.4 2.5 0.3
- 0.05 0.81 0.09 0.31 3.64 6.57 8.77 6.34 6.25 5.62 2.43 0.54 37.89 0.40 0.27 0.49 5.17 8.41 1.21 0.13 8.46 1.08 2.20 1.03 0.22 0.58 0.50 0.05 0.18 1.12 0.14
1072 –
1.3 –
1.4 248.1
0.63 111.56
than at present, its major part being covered by forest tundra and forest vegetation. The northern limit of the nemoral forest in the European Russia was 600– 700 km north of the present one. Therefore, the broad-leaved forest covered the main part of the Russian Plain. The climatic conditions were then favorable for arboreal species, which at present are characteristic for the regions of the West Europe with warmer oceanic climate. Such trees as hornbeam Ža dominant species of the broad-leaved forest at the Mikulino Interglacial., oaks Ž Quercus pubescens and Q. petraea., linden ŽTilia platyphyl-
Carbon storage, t = 10 9
los . and others now grow in the western part of Europe, reaching as far east as the Dnieper River valley. To the north, the subzone of the broad-leaved forest was succeeded by the spruce and mixed forest, which included the broad-leaved species in proportion diminishing towards the north. Broad-leaved forest steppe was spread in place of the modern East European steppe zone. In West Siberia, the distribution of vegetation was closer to the recent one, except for the presence of broad-leaved tree species both in the southern part of
A.A. Velichko et al.r Chemical Geology 159 (1999) 191–204 Fig. 2. Vegetation of the Northern Eurasia Žin the borders of FSU. during the Holocene optimum, 5.5–6 ka BP. According to Khotinsky ŽVelichko, in print., simplified. Explanation: see Table 2. 197
198
A.A. Velichko et al.r Chemical Geology 159 (1999) 191–204
Table 2 Phytomass and carbon storage in the vegetation of the Northern Eurasia Žin the borders of the FSU. during the Holocene optimum Žabout 5.5–6.0 ka BP. Vegetation
Area in thousand km2
Phytomass storage Specific values, Total ktrkm2 t = 10 9
Carbon storage, t = 10 9
1. Arctic desert 2. Tundra 3a. Birch forest-tundra 3b. Spruce and birch forest-tundra 3c. Larch forest-tundra 4a. Northern taiga spruce forest 4b. Middle taiga spruce forest 4c. Southern taiga spruce forest 5. Siberian pine and spruce middle taiga forest 6. Siberian pine–spruce–fir and spruce–fir southern taiga forest 7. Mountain dark coniferous forest 8. Birch–pine forest in Karelia 9. Birch forest 10. Beringian birch forest in Kamchatka 11. Spruce–larch northern taiga forest 12. Larch forest 13. Larch–pine forest 14. Larch–pine and pine light forest with steppe-like field layer 15. Siberian dwarf–pine elfin wood 16. Pine forest 17. Coniferous-broad-leaved forest 18a. Broad-leaved-coniferous Far East forest 19a. Broad-leaved Žoak, elm. lime. forest 19b. Pine-broad-leaved forest 20. Broad-leaved Far East forest 21. Meadow steppe combined with broad-leaved forest 22. Meadow steppe combined with birch forest 23. Meadow steppe combined with pine, birch and larch forest 24. Herb–grass steppe 25. Grass xerophytic steppe 26. Grass–sagebrush steppe Žsemidesert. 27. Desert 28. Tugai Žriverine complex with forest, bushes and meadows in Middle Asian river valeys. and oases 29. Mountain tundra combined with shrubs 30. Areas where vegetation has not been reconstructed Total
50 863 11 64 567 407 266 724 1298 968 559 133 625 123 1410 3612 195 110 82 24 690 197 1015 240 243 274 205 110 1524 1043 618 1480 234
- 0.1 1.3 1.6 2.5 3.1 16.7 22.8 31.1 20.5 25.8 22.8 18.3 21.3 11.2 24.3 13.2 24.2 17.4 6.8 21.4 26.3 31.4 32.5 20.5 23.6 13.0 6.5 7.4 1.5 1.0 0.7 1.2 9.2
- 0.1 1.1 - 0.1 0.2 1.8 6.8 6.1 22.5 26.6 25.0 12.7 2.4 13.3 1.4 34.3 47.7 4.7 1.9 0.6 0.5 18.1 6.2 33.0 4.9 5.7 3.6 1.3 0.8 2.3 1.0 0.4 1.8 2.2
- 0.05 0.50 - 0.05 0.09 0.81 3.06 2.75 10.12 11.97 11.25 5.71 1.08 5.99 0.63 15.43 21.46 2.11 0.85 0.27 0.23 8.14 2.79 14.85 2.21 2.57 1.62 0.58 0.36 1.03 0.45 0.18 0.81 0.99
740 286 –
1.3 – –
1.0 – 292.1
0.45 – 131.40
120% of the modern Žpotential. phytomass and carbon storage.
the forest zone, and in the north of the forest steppe. The vegetation in the area occupied at present by the larch forest experienced a dramatic change: dark coniferous forest occurred in its western part, while the eastern part was covered by birch and pine forest. Probably, the change has been caused by partial degradation of the permafrost.
In the Far East, both an area occupied by the broad-leaved species and their role in the plant communities increased considerably. Scarce data available on the steppe and desert vegetation indicate a milder type of the plant communities at the Mikulino optimum, such as a spread of semidesert vegetation over the northern part of the present-day desert zone.
A.A. Velichko et al.r Chemical Geology 159 (1999) 191–204 Fig. 3. Vegetation of the Northern Eurasia Žin the borders of FSU. during the Last Glacial Maximum, 18–20 ka BP. According to Grichuk ŽVelichko, in print., simplified. Explanation: see Table 3. 199
200
A.A. Velichko et al.r Chemical Geology 159 (1999) 191–204
Table 3 Phytomass and carbon storage in the vegetation of the Northern Eurasia during the maximum of the last, Valdai ŽWeichselian. glaciation Vegetation
Area in thousand km2
Phytomass storage Specific values, Total ktrkm2 t = 10 9
Carbon storage, t = 10 9
1. Arctic deserts combined with moss and low shrub–moss tundra 2. Arctic deserts combined with grass–moss tundra and with halophytes at the emerged parts of the continental shelf 3. Low shrub, moss and grass tundra, combined in the East with steppe communities 4. Sedge–cotton grass tundra and subarctic meadows with halophytes at the emerged parts of shelf 5. Grass–sagebrush steppe combined with sedge–cotton grass tundra 6. Mountain tundra with dwarf shrub communities and xerophytes on rocky slopes 7. Tundra and steppe communities combined with birch and larch open woodlands 8. Combination of mountain and lowland tundra and birch, spruce and Siberian pine woodlands 9. Spruce, larch and birch open woodlands 10. Birch open woodland combined with steppe communities 11. Shrub alder and Siberian dwarf–pine plant formations 12. Periglacial forest-steppe Žperiglacial steppe communities combined with birch and pine forest, with tundra elements and halophytes. 13. Periglacial steppe communities and birch, spruce and Siberian pine–pine forest Žwith tundra elements. 14. Meadow steppe and pine–birch forest with oak and elm 15. Herb–grass steppe combined with birch and larch forest 16. Periglacial steppe 17. Meadows combined with the primitive aggregations of halophytes 18. Mixed Žpine, larch and birch. and coniferous Žspruce and fir. forest in low mountains and plains 19. Pine, Siberian pine and birch forest with fir and spruce 20. Siberian pine forest with spruce, fir, larch and birch 21. Pine–birch and pine forest with steppe elements 22. Dark coniferous Žspruce, fir. forest with oak and lime tree in Europe, Siberian pine and lime in Siberia 23. Larch forest 24. Spruce–pine and birch forest with larch Žin the Far East. 25. Birch and spruce–Siberian pine forest with fir, oak and elm Žin the Far East. 26. Larch–Siberian pine and larch–spruce forest combined with steppe and tundra plant communities 27. Birch and larch–pine forest combined with meadow steppe 28. Herb–grass steppe combined with pine and birch forest 29. Larch, spruce–larch and birch open woodlands 30. Pine-broad-leaved and mixed forest in Crimea 31. Pine-oak and mixed South Ural forest 32. Grass and herb–grass steppe 33. Sagebrush, herb–sagebrush and salt bush steppe Žsemidesert. 34. Grass–sagebrush lowland and mountain steppe combined with the desert plant communities
276.7 2303.7
0.3 0.3
0.1 0.7
0.46 0.31
986.5
1.6
1.5
0.67
353.9
1.3
0.5
0.22
670.0
1.2
0.8
0.36
1709.9
1.0
1.7
0.76
482.5
2.3
1.1
0.49
1166.3
3.3
3.8
1.71
332.8 123.0 47.1 839.1
3.8 3.3 4.5 2.2
1.3 0.4 0.2 1.8
0.58 0.18 0.17 0.65
776.7
3.5
2.7
1.21
164.1 994.9 443.0 65.7
5.0 4.4 0.7 1.0
0.8 4.4 0.3 0.06
0.36 1.98 0.10 0.02
4.7
13.7
0.06
0.02
179.0 298.3 265.4 184.9
14.9 13.3 13.7 18.1
2.7 3.9 3.6 3.3
1.20 1.75 1.60 1.50
1466.9 263.4 99.3
11.6 17.2 18.8
17.0 4.5 1.9
7.65 2.00 0.85
645.9
3.3
2.1
0.90
56.1 85.0 176.0 11.7 21.5 447.7 717.0 1921.5
6.0 5.2 3.8 23.8 18.1 1.3 0.7 0.5
0.3 0,4 0.7 0.3 0.4 0.6 0.5 1.0
0.13 0.18 0.31 0.13 0.18 0.27 0.22 0.45
A.A. Velichko et al.r Chemical Geology 159 (1999) 191–204
201
Table 3 Žcontinued. Vegetation
Area in thousand km2
Phytomass storage Specific values, Total ktrkm2 t = 10 9
Carbon storage, t = 10 9
35. Semisavanna 36. Herb–grass steppe combined with the forest in river valleys 37. Shrub and salt bush desert 38. Sagebrush and ephemeral plant desert 39. Psammophitic bush desert 40. Mountain juniper and pistache open woodlands 41. High mountain tundra and dwarf shrub communities 42. Ice-sheets Total
84.5 66.2 12.0 128.6 29.6 11.4 470.1
1.1 0.7 0.3 0.2 0.8 0.6 1.3
0.1 - 0.1 - 0.1 - 0.1 - 0.1 - 0.1 0.6
0.04 - 0.01 - 0.01 - 0.01 - 0.01 - 0.01 0.27
66.1
29.94
–
–
27% of the modern Žpotential. phytomass and carbon storage.
In the areas where the floristic composition was similar to that of today, coenotic role of more thermofilous species increased. Thus, the proportion of fir was greater in the forests of the northeastern Europe, as well as in some parts of the West and Central Siberia. On the contrary, the role of spruce in the East European mixed forest diminished. In the southern part of its present-day range Žsouth of the Upper Volga valley. spruce was absent at the Mikulino optimum phase. Over the northern parts of the West and Central Siberia the taiga forest zone was similar to the modern one. On the whole, at the optimum of the Mikulino Interglacial plant formations with high specific values of the phytomass and carbon storage Žthose of the broad-leaved and mixed forests, and the meadow steppe. extended over greater areas than nowadays or at the Holocene climatic optimum. On the contrary, the areas occupied by formations with low phytomass storage Žsuch as larch forests and open woodlands, dry steppes and semideserts. were reduced. As the result, the total phytomass storage within the FSU territory amounted to 377.1 Gt, that of carbon, 169.7 Gt, which makes 155% of the modern values ŽTable 4..
4. Discussion The comparison of the calculated values of the phytomass storage in the terrestrial vegetation on the territory of FSU reveals large-scale oscillations between the warm and cold epochs Žinterglacial optimums, the Holocene optimum included, and the Late
Glacial maximum., as well as between warm epochs with different heat supply Žthe Holocene and Mikulino–Eemian optimums.. It is evident, that such changes constituted an important influence on the carbon balance during the Pleistocene and the Holocene. The comparison of the presented values of the phytomass and carbon storage in the North Eurasia at 5.5, 18 and 125 ka BP with the parameters obtained for East-European Plain ŽZelikson et al., 1998. show that the correlation of the values for Mikulino, as well as for the Holocene optimums, and present time is similar in both regions Žthe first value reaches about 150% and 120% of the second one, respectively.. During the Last Glacial Maximum, the phytomass and carbon storage was higher on the territory of North Eurasia because the degradation of the forest and woodland, as well as of the steppe vegetation in the continental areas of the Asian part of the territory was less expressed than in the East Europe. Our estimations are in good agreement with those made by Gliemeroth Ž1995. for the territory of Europe at the key intervals of the last 22,000 years. For instance, according to Gliemeroth, the biomass storage Žconsisting largely of the phytomass storage. for the Holocene optimum 7 ka BP amounted to about 116% of the modern potential one. The biomass storage in Europe at the Pleniglacial phase of the Late Wistulian Ž22 ka BP. was as low as 4.8% of the modern value. Similar estimations were made by Monserud et al. Ž1995. for Siberia, where the phytomass storage at the Middle Holocene Ž4.6–6.0 ka
202 A.A. Velichko et al.r Chemical Geology 159 (1999) 191–204 Fig. 4. Vegetation of the Northern Eurasia Žin the borders of FSU. during the Mikulino ŽEem. optimum, about 125 ka BP. According to Grichuk ŽVelichko, in print., simplified. Explanation: see Table 4.
A.A. Velichko et al.r Chemical Geology 159 (1999) 191–204
203
Table 4 Phytomass and carbon storage in the vegetation of the Northern Eurasia Žin the borders of FSU. during the optimum of Mikulino ŽEemian. Interglacial Žabout 125 ka BP. Vegetation
Area in thousand Phytomass storage Carbon storage, km2 t = 10 9 Specific values, Total ktrkm2 t = 10 9
1. Tundra 2. Spruce and larch forest-tundra 3. Birch forest with pine and spruce 4. Birch and pine open woodland 5. Birch and mixed forest 6. Spruce and birch forest with broad-leaved tree species 8. Dark coniferous forest with broad-leaved tree species 9. Coniferous-broad-leaved forest 10. Dark coniferous ŽSiberian pine, spruce, fir. forest 11. Birch forest with Siberian pine, spruce and broad-leaved tree species 12. Pine and birch light forest with oak an lime and steppe-like field layer 13. Larch forest 14. Larch forest with pine and birch 15. Siberian pine–pine and Siberian pine–spruce forest 16. Spruce–Siberian pine and pine forest with fir, larch, elm and lime 17a. Polydominant Far East coniferous-broad-leaved forest 17b. Polydominant coniferous-broad-leaved forest in Crimea and South Ukrain 18. Pine and birch forest 19. Mountain Siberian pine forest with spruce and larch 20. Hornbeam forest with oak and lime 21. Mixed hornbeam forest with Mongolian oak 22. Meadow steppe combined with hornbeam and oak forest 23. Meadow steppe combined with pine forest with elm, oak and lime 24. Meadow steppe combined with pine and birch forest 25. Meadow steppe combined with larch and birch forest 26. Grass steppe 27. Grass–sagebrush steppe Žsemidesert. 28. Sagebrush and salt bush desert 29. Psammophytic desert with Haloxylon and psammophillous bushes 30. High mountain woodlands, tundra-like and meadow plant formations 31. Semisavanna 32. Mountain grass communities combined with xerophillous bushes 33. Kamchatka birch woodland Total
629 342 223 506 1511 1285 205 311 813 1304 70 1681 1209 703 798 256 104
2.0 4.4 7.1 7 16.7 28 23.4 34.0 22.6 21.5 15.1 13.2 24.2 20.5 28.1 31.4 20.5
1.3 1.5 1.6 3.5 25.2 36.0 4.8 10.6 18.4 28.0 1.0 22.2 29.3 14.4 224 8.0 2.1
0.59 0.68 0.72 1.57 11.34 16.20 2.16 4.77 8.28 12.60 0.45 9.99 13.19 6.48 10.08 3.60 0.95
720 307 2048 163 941 1023 498 53 392 729 496 591 795 143 55 96 –
23.1 20.2 35.0 23.6 13.0 9.6 7.2 7.2 1.3 0.7 6.7 19.6 5.4 3.5 1.3 11.2 –
16.6 6.2 71.7 3.8 12.2 9.8 3.6 0.4 0.45 0.5 3.3 11.6 4.3 0.7 0.1 1.1 377.1
7.47 2.79 32.27 1.71 5.49 4.41 1.62 0.18 0.20 0.22 1.49 5.22 1.94 0.32 0.05 0.50 169.7
155% of the modern Žpotential. phytomass and carbon storage.
BP. reached 105 Gt, that is, 122% of the phytomass storage in the modern potential vegetation Ž85.9 Gt..
References Adams, J.M., Faure, H., Faure-Denard, L., McGlade, J.M., Woodward, F.I., 1990. Increases in terrestrial carbon storage from the Last Glacial Maximum to the present. Nature 348, 711– 714.
Ajtay, G.L., Ketner, P., Duvigneaud, P., 1979. Terrestrial primary production and phytomass. In: Bolin, B., Degens, E.T., Kempe, S., Ketner, P. ŽEds.., The Global Carbon Cycle. SCOPE 13, Wiley, Chichester, pp. 123–181. Alekhin, V.V., 1951. Rastitel’nost’ SSSR. Sovetskaya Nauka, Moscow, 512 pp. Žin Russian.. Bazilevich, N.I., 1993. Biologicheskaya productivnost’ ecosistem Severnoi Evrazii. Nauka, Moscow, 293 pp. Žin Russian.. Gliemeroth, A.-K., 1995. Palaookologische Untersuchungen uber ¨ die letzten 22000 Jahre in Europa. Gustav Fischer Verlag, Stuttgart, 252 pp.
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Grichuk, V.P., 1979. Metodika interpretatsii paleobotanicheskikh materialov dlya resheniya zadach stratigrafii i korrelyatsii pozdnego kainozoya. In: Grichuk, V.P. ŽEd.., Palinologicheskiye issledovaniya na severo-vostoke SSSR. Akademiya Nauk SSSR, Dal’nevostochny Nauchny Tsentr, Vladivostok, pp. 5–22 Žin Russian.. Kuminova, A.V., 1960. Rastitel’nyi pokrov Altaya. Izdatel’stvo AN SSSR. Sibirskoye Otdelenie. Novosibirsk, 450 pp. Žin Russian.. Monserud, R.A., Denissenko, O.V., Kolchugina, T.P., Tchebakova, N.M., 1995. Global Biogeochemical Cycles 9 Ž2., 213–226. Rastitel’nost’ Evropeiskoi chasti SSSR, 1980. In: Gribov, S.A., Isachenko, T.I., Lavrenko, E.M. ŽEds.., Nauka, Leningradskoye otdelenie, Leningrad, 429 pp. Žin Russian..
Sochava, V.B., et al., 1964. Fiziko-geograficheskiy atlas mira, 1964. Akademiya Nauk SSSR i Glavnoye Upravleniye Geodezii i Kartografii GGK. SSSR, Moscow, pp. 280–288 Žin Russian.. Velichko, A.A. ŽEd.., 1984. Late Quaternary environments of the Soviet Union, University of Minnesota Press, Minneapolis, 327 pp. Velichko, A.A., ŽEd.., in print. Razvitiye landshaftov i klimata territorii Severnoi Evrazii. Atlas-monografiya, tom 2 Žin Russian.. Zelikson, E.M., Borisova, O.K., Kremenetsky, C.V., Velichko, A.A., 1998. Phytomass and carbon storage during the Eemian optimum, Late Weichselian maximum and Holocene optimum in Eastern Europe. Global and Planetary Change 16–17, pp. 181–195.
Vegetation, phytomass and carbon storage in Northern Eurasia during the last glacial–interglacial cycle and the Holocene A.A. Velichko ) , E.M. Zelikson, O.K. Borisova Laboratory of EÕolutionary Geography, Institute of Geography RAS, Staromonetny, 29 Moscow, Russian Federation Received 7 April 1998; received in revised form 10 September 1998; accepted 27 November 1998
Abstract The phytomass Žthe biomass of terrestrial vegetation. is one of the main reservoirs of carbon, as carbon makes up approximately 0.45 of the phytomass by weight wAjtay, G.L., Ketner, P., Duvigneaud, P., 1979. Terrestrial primary production and phytomass. In: Bolin, B., Degens, E.T., Kempe, S., Ketner, P. ŽEds.., The Global Carbon Cycle, SCOPE 13, Wiley, Chichester, pp. 123–181.x. During the glacial–interglacial climatic rhythm both composition and geographical distribution of vegetation over Northern Eurasia have been repeatedly subjected to major changes, accompanied by corresponding changes of phytomass and carbon storage. Of special interest are three key intervals within the last 125,000 years: the Mikulino ŽEem. Interglacial optimum, about 125 ka BP; the Last Glacial maximum, 18–20 ka BP and the Holocene optimum, 5.5–6 ka BP. These intervals correspond to the extreme states of the environment. Vegetation which existed in Northern Eurasia 125, 18–20 and 5.5–6 ka BP, accumulated 377.1 Gt, 66.1 Gt and 292.1 Gt of phytomass, which corresponds to 169.7 Gt, 29.9 Gt and 131.4 Gt of carbon, respectively. Compared to present-day carbon storage in the phytomass of potential vegetation Žtaken as 100%., these values are 155%, 27% and 120%, respectively. q 1999 Elsevier Science B.V. All rights reserved. Keywords: Vegetation; Phytomass; Carbon
1. Introduction The phytomass of terrestrial vegetation is one of the main reservoirs of carbon storage. Carbon makes up about 45% of the phytomass by weight ŽAjtay et al., 1979.. During the last glacial–interglacial climatic cycle vegetation cover was subjected to major changes. As a result, the phytomass and carbon storage also changed. Phytomass and carbon storage
)
Corresponding author. Tel.: q7-095-2380298; fax: q7-0959590033; e-mail: [email protected]
in terrestrial vegetation are reconstructed for four periods of time, corresponding to different values of global heat supply: Ž1. for the mean global temperature 18C higher than the present-day one Žthe climatic optimum of the Holocene.; Ž2. for the maximum cooling of the Last Ice Age, when the mean global temperature was 3–48C lower than at present; Ž3. for the mean global temperature approximately 28C higher than the present-day one Žthe optimum of the last, Mikulinos Eem Interglacial.; Ž4. for the present-day climatic conditions Žmodern carbon storage in terrestrial phytomass has been calculated for potential Žreconstructed. vegetation..
0009-2541r99r$ - see front matter q 1999 Elsevier Science B.V. All rights reserved. PII: S 0 0 0 9 - 2 5 4 1 Ž 9 9 . 0 0 0 2 9 - 7
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2. Methods Estimations of phytomass storage are mainly achieved by modelling, or by reconstruction of the spatial distribution of terrestrial biomes of high taxonomic rank ŽAdams et al., 1990.. This article is based on more detailed reconstruction of the vegetation cover, taking into account palynological Žin some cases also palaeocarpological. data, as well as ecology of modern plants and plant communities. The only source of information on specific values of phytomass and carbon storage in the vegetation of the past is from modern plant communities, which can be considered their closest analogues. The specific values for specific plant communities and especially for communities formed by the same dominant species in different climatic and landscape conditions vary in a broad range, depending on the floristic composition of plant communities, the canopy density in the forest, the density of herbaceous cover, the number of storeys in plant communities. These features depend in their turn on the composition of species, on climatic and soil conditions, and other characteristics of the environment. For example, the mean specific value of phytomass storage ŽSVPS. for the broad-leaved forest of the Russian Plain reaches 22 ktrkm2 in the area between the Oka and Don Rivers, 33 ktrkm2 between Pripyat’ and Middle Dnieper, and up to 40 ktrkm2 between the Dniestr and Danube valleys ŽBazilevich, 1993.. Thus, an important methodological question is how and by which criteria we should choose an analogue for a reconstruction of the phytomass storage. The quantitative correlation of components in pollen spectra obtained from the sediments of certain ages correspond to the type of vegetation that existed during the time interval under study and the composition of its dominants. Pollen analysis enables us to distinguish the dominants of certain plant communities at the taxonomic rank of genera for arboreal plants, or families for herbaceous plants. For reconstruction of vegetation, paleofloristic data are especially informative as some of the plant species are closely connected with the communities of a definite type Žso-called indicative plants.. If such species are identified in a fossil flora, one can reconstruct ancient plant communities using modern ecological
demands and coenotic connections of indicative plants. Bazilevich Ž1993. estimated SVPS for the modern plant communities in the territory of the former Soviet Union. The monograph contains SVPS for the main vegetation types within the FSU territory Žmore than 2500 estimations.. We used these estimations to calculate the phytomass and carbon storage in the vegetation of the Northern Eurasia for the above mentioned key intervals of the past and for the modern potential vegetation. The SVPS for the modern zonal vegetation types were calculated as mean values of all the estimations for given vegetation type within the area, published by Bazilevich. For example, this author gave SVPS for different types of the middle taiga spruce forests for three regions of East Europe Žwhich were based on primary data on 18 key-sites.. The phytomass storage is 220.50 trha, 227.57 trha and 236.55 trha in western, central and eastern parts of the subzone, respectively; the mean value is 228 trha, or 22.8 ktrkm2 . For southern taiga subzone of the East European spruce forest, the same author gives three regional specific values Ž227.77 trha, 291.38 trha, 359.89 trha. calculated on the basis of 38 key-sites. The mean value for the southern taiga is 311.35 trha Žapproximately 31.1 ktrkm2 .. SVPS for complex types of vegetation were calculated using similar procedure. According to Bazilevich Ž1993., the phytomass storage of oak forest within the forest-steppe zone is 293.7 trha Žthe mean value is derived from measurements from 39 key-sites., that of linden forest is 192.8 trha Ž3 key-sites.. Thus, the mean value for forest vegetation in the forest-steppe zone is 243,3 trha. The specific phytomass storage in the meadow steppe vegetation was estimated for three regions by 18 key-sites as 12.7 trha, 16.5 trha and 10.6 trha, the mean value being 13.30 trha. It is supposed that in the foreststeppe, under natural Žpre-agricultural. conditions, the woodland occupied about one half of the area ŽRastitel’nost’ Evropeiskoi chasti SSSR, 1980.. In that case, the mean specific value of the phytomass storage for the forest-steppe zone can be calculated simply as Ž243.26 q 13.30.: 2 s 128.28 trha Ž12.8 ktrkm2 ..
A.A. Velichko et al.r Chemical Geology 159 (1999) 191–204
Similarly, the SVPS can be estimated for the forest-tundra. At present, woods occupy 2% to 3% of the area in the north of the subzone and 20% to 30% in its southern part ŽAlekhin, 1951.. The rest of the area is covered by tundra and marsh vegetation. According to Bazilevich Ž1993., marsh communities are very close to tundra by SVPS. To choose modern analogues to the vegetation types of the Mikulino ŽEemian. and Valdai ŽLast Glacial maximum. plant communities, one has to use various approaches, depending upon availability of paleofloristic data. It is especially difficult to estimate SVPS for the periglacial steppes and foreststeppes, which occupied vast areas in Eurasia during glacial epochs, because such communities have no complete analogue in the present-day vegetation. If the paleofloristic data available are sufficient, we can use a method of modern concentration area of plant species of the fossil flora, that is the region where the majority of plant species—components of certain fossil flora—grow at present ŽGrichuk, 1979.. It was shown that modern vegetation of such a region represents the closest analogue of the one existed at the site during the studied time interval. For example, the SVPS for the spruce and birch forest with broad-leaved trees, spread over the northern part of the East Europe during the Mikulino optimum Žunit 6 on the map., was estimated by the following procedure. The composition of species typical for such forest in Mikulino Interglacial can be found at present in the territory adjacent to Fennish and Riga Gulfs of the Baltic Sea. The estimations of the SVPS for modern forests within the area, based on 11 key-sites, are published by Bazilevich: 220.50 and 247.16 trha, the mean of these values is 233.83 trha Žapproximately 23.4 ktrkm2 .. With the use of the method, modern plant communities closest to the periglacial steppe of the central East Europe at the maximum of the Valdai Glacial were identified: those of the dry steppe in the cold and continental Altai region Žabout 6 trha, Kuminova, 1960.. 1
1
We accepted here the value of 0.7 ktrkm2 , taking into consideration the presence of arboreal plant communities with higher SVPS in the periglacial steppe vegetation, though such communities occupied only a small part of the area.
193
If the paleofloristic data available are insufficient to apply the method of the modern concentration regions, one can take into consideration specific features of the past vegetation, indicated by the presence of characteristic plants in the fossil flora. One can suppose that such estimations based on the floristic indications are less reliable than those calculated by SVPS in the regions of maximum modern concentration of the plant species—components of the fossil flora. But usually the estimations attained by the two methods are similar, for example, the SVPS characteristic for the modern analogues of the periglacial steppe found by floristic indicators Ždry and salt steppes in East Europe. are also close to 6 trha Ž6.50, 5.76 and 5.70 trha, according to Bazilevich.. A similar approach was used in the case when present-day plant communities in the region of concentration of the fossil flora do not correspond to those of the past vegetation. For example, the closest modern floristic analogue to the broad-leaved forest with hornbeam, that occupied a major part of East Europe during the Mikulino Interglacial, can be found in the Upper Elba River catchment basin. It means, that at present, the majority of plant species, which grew in the central region of the East European Plain during the Mikulino Interglacial, can be found in the area. As the broad-leaved forests with hornbeam at the Elba River basin occupy places with the most fertile soil Žbroadly used for agriculture for a long time. they are considerably disturbed, so that their modern SVPS cannot be used for reconstruction. Instead, the specific values of the other broad-leaved forest with similar composition of dominant trees and coenotic structure were used for calculations of the phytomass storage in the floristically rich broadleaved forest of the Mikulino Interglacial optimum. The vegetation maps compiled by Khotinski for the Holocene optimum and by Grichuk for the Valdai Glacial maximum and the Mikulino Interglacial optimum ŽVelichko, in print. were used to calculate areas occupied by various vegetation types. All the maps were based on abundant palynological data: information on 290, 285 and about 400 sites was used to compile the vegetation maps of the Mikulino Interglacial optimum, Valdai Glacial maximum and the Holocene optimum, respectively. First drafts of these maps were published in the monograph Late
194
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Quaternary environments of the Soviet Union ŽVelichko, 1984., where the methods of vegetation reconstruction, used by above mentioned authors, were described. To estimate the phytomass and carbon storage in the modern potential vegetation, the map by Sochava et al. Ž1964. was used Ždisturbances of the vegetation due to agricultural and industrial activities were not taken into consideration.. All the four maps were simplified by merging the areas of plant communities with similar features and phytomass storage indexes. 3. Results The total phytomass storage in the modern potential Õegetation in the Northern Eurasia within the FSU boundaries amounts to 248.1 Gt, implying a carbon content of 111.6 Gt. The bulk of the storage is made up by dark coniferous and larch forest, the two most widespread formations within the area ŽFig. 1 and Table 1.. The vegetation formations that spread over the East Europe at the second half of the Atlantic period of the Holocene Ž5.5–6.0 ka BP., were close to their modern analogues. But due to the warmer climate, their ranges, and especially their northern boundaries, were different from the present-day ones ŽFig. 2.. According to the reconstruction of vegetation made by Khotinski, the zonal structure of vegetation at the Holocene optimum was similar to that of today. In the north of Eurasia the tundra zone was considerably narrower than at present. The forest tundra reached the seashore in the north of the Kola Peninsula. It was also spread over the southern parts of the Yamal and Taimyr Peninsulas. Only in the northeast of Eurasia was the northern tree line close to the present-day one. The area of the forest zone was considerably greater than today, especially that of dark coniferous forest. Coniferous-broad-leaved forest in the East Europe occupied the present-day area of the southern taiga subzone, while the northern limit of the broad-leaved forest was close to the modern one, or somewhat shifted to the north. On the whole, at the Holocene optimum an area of the nemoral broad-leaved forest exceeded the present one, while that of the forest steppe was smaller than now. In West Siberia, the herb–grass steppe occupied a larger area than at present. Comparison be-
tween the modern vegetation map and that of the Holocene optimum shows that at the Holocene optimum, the areas of plant formations with high values of the phytomass storage were greater than today due to increased heat and moisture supply. Therefore, total phytomass and carbon storage in the Northern Eurasia exceeded the modern values. The phytomass storage reached 292.1 Gt, that of carbon being 131.4 Gt, or 120% of the modern potential value ŽTable 2.. Plant communities that spread over Northern Eurasia during the Maximum cooling of the Last Glacial epoch, 18–20 ka BP, differed from the modern ones by their structure and other features. According to the reconstruction of vegetation made by Grichuk, the major part of the area was occupied by communities of periglacial tundra Žin the north. and periglacial steppe types ŽFig. 3.. The tree species least demanding to the environmental conditions, such as birch, pine, larch, and spruce, formed small woodland patches within the periglacial tundra and steppe zones. The boreal forest did not exist in East Europe, but survived in the southern part of Siberia and in the Far East, in relatively mild conditions of mountain regions. Due to a severe climate of the ice age, the forest belt there was narrow and discontinuous, the woodlands being very open with low quality of tree stands. Consequently, the phytomass and carbon storage in such forests was low. An area occupied by the vegetation of nemoral type has been even more reduced. Small patches of the broad-leaved forest during the ice age were confined to Crimea, Caucasus, Southern Urals, and southern part of the Far East. The total phytomass and carbon storage in the scanty vegetation of the ice age was drastically reduced compared to the one characteristic for the interglacial epochs ŽTable 3.. For the stage of maximum cooling of the Last Glacial, they amounted to 27% of the modern values: the phytomass storage did not exceed 66.1 Gt, that of carbon, 29.9 Gt. At the Mikulino Interglacial optimum, the northern boundary of the forest zone in the European Russia shifted 200–300 km to the north compared to its present-day position, so that the forest reached the coast of the Arctic Ocean ŽFig. 4.. In Siberia, the tree line shifted towards north of the modern one by 450–550 km. The area of tundra was then far smaller
A.A. Velichko et al.r Chemical Geology 159 (1999) 191–204
Fig. 1. Modern vegetation of the Northern Eurasia Žin the borders of FSU.. According to Sochava et al. Ž1964., simplified. Explanation: see Table 1. 195
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Table 1 Phytomass and carbon storage in the present-day potential vegetation in the Northern Eurasia Žin the borders of FSU. Vegetation
Area in thousand km2
Phytomass storage Specific values, Total ktrkm2 t = 10 9
1. Arctic desert 2. Tundra 3a. Birch forest-tundra 3c. Larch forest-tundra 4a. Northern taiga spruce forest 4b. Middle taiga spruce forest 4c. Southern taiga spruce forest 5. Siberian pine and spruce middle taiga forest 6. Siberian pine–spruce–fir and spruce–fir southern taiga forest 7. Mountain dark coniferous forest 9. Birch forest 10. Beringian birch forest in Kamchatka 12. Larch forest 13. Larch–pine forest 14. Larch–pine and pine light forest with steppe-like field layer 15. Siberian dwarf–pine elfin wood 16. Pine swamp forest 17. Coniferous-broad-leaved forest 18a. Broad-leaved-coniferous Far East forest 18b. Pine-broad-leaved Crimean forest 19. Broad-leaved Žoak, elm. lime. forest 20. Broad-leaved Far East forest 21. Meadow steppe combined with broad-leaved forest 22. Meadow steppe combined with birch forest 23. Meadow steppe combined with pine, birch and larch forest 24. Herb–grass steppe 25a. Grass xerophytic steppe 25b. Mountain steppe 26. Grass–sagebrush steppe Žsemidesert. 27. Desert 28. Tugai Žriverine complex with forest, bushes and meadows in Middle Asian river valeys. and oases 29. Mountain tundra combined with shrubs Total
101 1362 105 230 488 640 626 687 540 551 253 110 6380 39 37 165 536 711 88 18 579 103 380 351 68 850 1087 38 623 2143 37
0.1 1.3 1.6 3.1 16.7 22.8 31.1 20.5 25.8 22.8 21.3 11.2 13.2 24.2 17.4 6.8 21.4 26.3 31.4 20.5 32.5 23.6 13.0 6.5 7.4 1.5 1.0 1.9 0.7 1.2 9.2
- 0.1 1.8 0.2 0.7 8.1 14.6 19.5 14.1 13.9 12.5 5.4 1.2 84.2 0.9 0.6 1.1 11.5 18.7 2.7 0.3 18.8 2.4 4.9 2.3 0.5 1.3 1,1 0.1 0.4 2.5 0.3
- 0.05 0.81 0.09 0.31 3.64 6.57 8.77 6.34 6.25 5.62 2.43 0.54 37.89 0.40 0.27 0.49 5.17 8.41 1.21 0.13 8.46 1.08 2.20 1.03 0.22 0.58 0.50 0.05 0.18 1.12 0.14
1072 –
1.3 –
1.4 248.1
0.63 111.56
than at present, its major part being covered by forest tundra and forest vegetation. The northern limit of the nemoral forest in the European Russia was 600– 700 km north of the present one. Therefore, the broad-leaved forest covered the main part of the Russian Plain. The climatic conditions were then favorable for arboreal species, which at present are characteristic for the regions of the West Europe with warmer oceanic climate. Such trees as hornbeam Ža dominant species of the broad-leaved forest at the Mikulino Interglacial., oaks Ž Quercus pubescens and Q. petraea., linden ŽTilia platyphyl-
Carbon storage, t = 10 9
los . and others now grow in the western part of Europe, reaching as far east as the Dnieper River valley. To the north, the subzone of the broad-leaved forest was succeeded by the spruce and mixed forest, which included the broad-leaved species in proportion diminishing towards the north. Broad-leaved forest steppe was spread in place of the modern East European steppe zone. In West Siberia, the distribution of vegetation was closer to the recent one, except for the presence of broad-leaved tree species both in the southern part of
A.A. Velichko et al.r Chemical Geology 159 (1999) 191–204 Fig. 2. Vegetation of the Northern Eurasia Žin the borders of FSU. during the Holocene optimum, 5.5–6 ka BP. According to Khotinsky ŽVelichko, in print., simplified. Explanation: see Table 2. 197
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Table 2 Phytomass and carbon storage in the vegetation of the Northern Eurasia Žin the borders of the FSU. during the Holocene optimum Žabout 5.5–6.0 ka BP. Vegetation
Area in thousand km2
Phytomass storage Specific values, Total ktrkm2 t = 10 9
Carbon storage, t = 10 9
1. Arctic desert 2. Tundra 3a. Birch forest-tundra 3b. Spruce and birch forest-tundra 3c. Larch forest-tundra 4a. Northern taiga spruce forest 4b. Middle taiga spruce forest 4c. Southern taiga spruce forest 5. Siberian pine and spruce middle taiga forest 6. Siberian pine–spruce–fir and spruce–fir southern taiga forest 7. Mountain dark coniferous forest 8. Birch–pine forest in Karelia 9. Birch forest 10. Beringian birch forest in Kamchatka 11. Spruce–larch northern taiga forest 12. Larch forest 13. Larch–pine forest 14. Larch–pine and pine light forest with steppe-like field layer 15. Siberian dwarf–pine elfin wood 16. Pine forest 17. Coniferous-broad-leaved forest 18a. Broad-leaved-coniferous Far East forest 19a. Broad-leaved Žoak, elm. lime. forest 19b. Pine-broad-leaved forest 20. Broad-leaved Far East forest 21. Meadow steppe combined with broad-leaved forest 22. Meadow steppe combined with birch forest 23. Meadow steppe combined with pine, birch and larch forest 24. Herb–grass steppe 25. Grass xerophytic steppe 26. Grass–sagebrush steppe Žsemidesert. 27. Desert 28. Tugai Žriverine complex with forest, bushes and meadows in Middle Asian river valeys. and oases 29. Mountain tundra combined with shrubs 30. Areas where vegetation has not been reconstructed Total
50 863 11 64 567 407 266 724 1298 968 559 133 625 123 1410 3612 195 110 82 24 690 197 1015 240 243 274 205 110 1524 1043 618 1480 234
- 0.1 1.3 1.6 2.5 3.1 16.7 22.8 31.1 20.5 25.8 22.8 18.3 21.3 11.2 24.3 13.2 24.2 17.4 6.8 21.4 26.3 31.4 32.5 20.5 23.6 13.0 6.5 7.4 1.5 1.0 0.7 1.2 9.2
- 0.1 1.1 - 0.1 0.2 1.8 6.8 6.1 22.5 26.6 25.0 12.7 2.4 13.3 1.4 34.3 47.7 4.7 1.9 0.6 0.5 18.1 6.2 33.0 4.9 5.7 3.6 1.3 0.8 2.3 1.0 0.4 1.8 2.2
- 0.05 0.50 - 0.05 0.09 0.81 3.06 2.75 10.12 11.97 11.25 5.71 1.08 5.99 0.63 15.43 21.46 2.11 0.85 0.27 0.23 8.14 2.79 14.85 2.21 2.57 1.62 0.58 0.36 1.03 0.45 0.18 0.81 0.99
740 286 –
1.3 – –
1.0 – 292.1
0.45 – 131.40
120% of the modern Žpotential. phytomass and carbon storage.
the forest zone, and in the north of the forest steppe. The vegetation in the area occupied at present by the larch forest experienced a dramatic change: dark coniferous forest occurred in its western part, while the eastern part was covered by birch and pine forest. Probably, the change has been caused by partial degradation of the permafrost.
In the Far East, both an area occupied by the broad-leaved species and their role in the plant communities increased considerably. Scarce data available on the steppe and desert vegetation indicate a milder type of the plant communities at the Mikulino optimum, such as a spread of semidesert vegetation over the northern part of the present-day desert zone.
A.A. Velichko et al.r Chemical Geology 159 (1999) 191–204 Fig. 3. Vegetation of the Northern Eurasia Žin the borders of FSU. during the Last Glacial Maximum, 18–20 ka BP. According to Grichuk ŽVelichko, in print., simplified. Explanation: see Table 3. 199
200
A.A. Velichko et al.r Chemical Geology 159 (1999) 191–204
Table 3 Phytomass and carbon storage in the vegetation of the Northern Eurasia during the maximum of the last, Valdai ŽWeichselian. glaciation Vegetation
Area in thousand km2
Phytomass storage Specific values, Total ktrkm2 t = 10 9
Carbon storage, t = 10 9
1. Arctic deserts combined with moss and low shrub–moss tundra 2. Arctic deserts combined with grass–moss tundra and with halophytes at the emerged parts of the continental shelf 3. Low shrub, moss and grass tundra, combined in the East with steppe communities 4. Sedge–cotton grass tundra and subarctic meadows with halophytes at the emerged parts of shelf 5. Grass–sagebrush steppe combined with sedge–cotton grass tundra 6. Mountain tundra with dwarf shrub communities and xerophytes on rocky slopes 7. Tundra and steppe communities combined with birch and larch open woodlands 8. Combination of mountain and lowland tundra and birch, spruce and Siberian pine woodlands 9. Spruce, larch and birch open woodlands 10. Birch open woodland combined with steppe communities 11. Shrub alder and Siberian dwarf–pine plant formations 12. Periglacial forest-steppe Žperiglacial steppe communities combined with birch and pine forest, with tundra elements and halophytes. 13. Periglacial steppe communities and birch, spruce and Siberian pine–pine forest Žwith tundra elements. 14. Meadow steppe and pine–birch forest with oak and elm 15. Herb–grass steppe combined with birch and larch forest 16. Periglacial steppe 17. Meadows combined with the primitive aggregations of halophytes 18. Mixed Žpine, larch and birch. and coniferous Žspruce and fir. forest in low mountains and plains 19. Pine, Siberian pine and birch forest with fir and spruce 20. Siberian pine forest with spruce, fir, larch and birch 21. Pine–birch and pine forest with steppe elements 22. Dark coniferous Žspruce, fir. forest with oak and lime tree in Europe, Siberian pine and lime in Siberia 23. Larch forest 24. Spruce–pine and birch forest with larch Žin the Far East. 25. Birch and spruce–Siberian pine forest with fir, oak and elm Žin the Far East. 26. Larch–Siberian pine and larch–spruce forest combined with steppe and tundra plant communities 27. Birch and larch–pine forest combined with meadow steppe 28. Herb–grass steppe combined with pine and birch forest 29. Larch, spruce–larch and birch open woodlands 30. Pine-broad-leaved and mixed forest in Crimea 31. Pine-oak and mixed South Ural forest 32. Grass and herb–grass steppe 33. Sagebrush, herb–sagebrush and salt bush steppe Žsemidesert. 34. Grass–sagebrush lowland and mountain steppe combined with the desert plant communities
276.7 2303.7
0.3 0.3
0.1 0.7
0.46 0.31
986.5
1.6
1.5
0.67
353.9
1.3
0.5
0.22
670.0
1.2
0.8
0.36
1709.9
1.0
1.7
0.76
482.5
2.3
1.1
0.49
1166.3
3.3
3.8
1.71
332.8 123.0 47.1 839.1
3.8 3.3 4.5 2.2
1.3 0.4 0.2 1.8
0.58 0.18 0.17 0.65
776.7
3.5
2.7
1.21
164.1 994.9 443.0 65.7
5.0 4.4 0.7 1.0
0.8 4.4 0.3 0.06
0.36 1.98 0.10 0.02
4.7
13.7
0.06
0.02
179.0 298.3 265.4 184.9
14.9 13.3 13.7 18.1
2.7 3.9 3.6 3.3
1.20 1.75 1.60 1.50
1466.9 263.4 99.3
11.6 17.2 18.8
17.0 4.5 1.9
7.65 2.00 0.85
645.9
3.3
2.1
0.90
56.1 85.0 176.0 11.7 21.5 447.7 717.0 1921.5
6.0 5.2 3.8 23.8 18.1 1.3 0.7 0.5
0.3 0,4 0.7 0.3 0.4 0.6 0.5 1.0
0.13 0.18 0.31 0.13 0.18 0.27 0.22 0.45
A.A. Velichko et al.r Chemical Geology 159 (1999) 191–204
201
Table 3 Žcontinued. Vegetation
Area in thousand km2
Phytomass storage Specific values, Total ktrkm2 t = 10 9
Carbon storage, t = 10 9
35. Semisavanna 36. Herb–grass steppe combined with the forest in river valleys 37. Shrub and salt bush desert 38. Sagebrush and ephemeral plant desert 39. Psammophitic bush desert 40. Mountain juniper and pistache open woodlands 41. High mountain tundra and dwarf shrub communities 42. Ice-sheets Total
84.5 66.2 12.0 128.6 29.6 11.4 470.1
1.1 0.7 0.3 0.2 0.8 0.6 1.3
0.1 - 0.1 - 0.1 - 0.1 - 0.1 - 0.1 0.6
0.04 - 0.01 - 0.01 - 0.01 - 0.01 - 0.01 0.27
66.1
29.94
–
–
27% of the modern Žpotential. phytomass and carbon storage.
In the areas where the floristic composition was similar to that of today, coenotic role of more thermofilous species increased. Thus, the proportion of fir was greater in the forests of the northeastern Europe, as well as in some parts of the West and Central Siberia. On the contrary, the role of spruce in the East European mixed forest diminished. In the southern part of its present-day range Žsouth of the Upper Volga valley. spruce was absent at the Mikulino optimum phase. Over the northern parts of the West and Central Siberia the taiga forest zone was similar to the modern one. On the whole, at the optimum of the Mikulino Interglacial plant formations with high specific values of the phytomass and carbon storage Žthose of the broad-leaved and mixed forests, and the meadow steppe. extended over greater areas than nowadays or at the Holocene climatic optimum. On the contrary, the areas occupied by formations with low phytomass storage Žsuch as larch forests and open woodlands, dry steppes and semideserts. were reduced. As the result, the total phytomass storage within the FSU territory amounted to 377.1 Gt, that of carbon, 169.7 Gt, which makes 155% of the modern values ŽTable 4..
4. Discussion The comparison of the calculated values of the phytomass storage in the terrestrial vegetation on the territory of FSU reveals large-scale oscillations between the warm and cold epochs Žinterglacial optimums, the Holocene optimum included, and the Late
Glacial maximum., as well as between warm epochs with different heat supply Žthe Holocene and Mikulino–Eemian optimums.. It is evident, that such changes constituted an important influence on the carbon balance during the Pleistocene and the Holocene. The comparison of the presented values of the phytomass and carbon storage in the North Eurasia at 5.5, 18 and 125 ka BP with the parameters obtained for East-European Plain ŽZelikson et al., 1998. show that the correlation of the values for Mikulino, as well as for the Holocene optimums, and present time is similar in both regions Žthe first value reaches about 150% and 120% of the second one, respectively.. During the Last Glacial Maximum, the phytomass and carbon storage was higher on the territory of North Eurasia because the degradation of the forest and woodland, as well as of the steppe vegetation in the continental areas of the Asian part of the territory was less expressed than in the East Europe. Our estimations are in good agreement with those made by Gliemeroth Ž1995. for the territory of Europe at the key intervals of the last 22,000 years. For instance, according to Gliemeroth, the biomass storage Žconsisting largely of the phytomass storage. for the Holocene optimum 7 ka BP amounted to about 116% of the modern potential one. The biomass storage in Europe at the Pleniglacial phase of the Late Wistulian Ž22 ka BP. was as low as 4.8% of the modern value. Similar estimations were made by Monserud et al. Ž1995. for Siberia, where the phytomass storage at the Middle Holocene Ž4.6–6.0 ka
202 A.A. Velichko et al.r Chemical Geology 159 (1999) 191–204 Fig. 4. Vegetation of the Northern Eurasia Žin the borders of FSU. during the Mikulino ŽEem. optimum, about 125 ka BP. According to Grichuk ŽVelichko, in print., simplified. Explanation: see Table 4.
A.A. Velichko et al.r Chemical Geology 159 (1999) 191–204
203
Table 4 Phytomass and carbon storage in the vegetation of the Northern Eurasia Žin the borders of FSU. during the optimum of Mikulino ŽEemian. Interglacial Žabout 125 ka BP. Vegetation
Area in thousand Phytomass storage Carbon storage, km2 t = 10 9 Specific values, Total ktrkm2 t = 10 9
1. Tundra 2. Spruce and larch forest-tundra 3. Birch forest with pine and spruce 4. Birch and pine open woodland 5. Birch and mixed forest 6. Spruce and birch forest with broad-leaved tree species 8. Dark coniferous forest with broad-leaved tree species 9. Coniferous-broad-leaved forest 10. Dark coniferous ŽSiberian pine, spruce, fir. forest 11. Birch forest with Siberian pine, spruce and broad-leaved tree species 12. Pine and birch light forest with oak an lime and steppe-like field layer 13. Larch forest 14. Larch forest with pine and birch 15. Siberian pine–pine and Siberian pine–spruce forest 16. Spruce–Siberian pine and pine forest with fir, larch, elm and lime 17a. Polydominant Far East coniferous-broad-leaved forest 17b. Polydominant coniferous-broad-leaved forest in Crimea and South Ukrain 18. Pine and birch forest 19. Mountain Siberian pine forest with spruce and larch 20. Hornbeam forest with oak and lime 21. Mixed hornbeam forest with Mongolian oak 22. Meadow steppe combined with hornbeam and oak forest 23. Meadow steppe combined with pine forest with elm, oak and lime 24. Meadow steppe combined with pine and birch forest 25. Meadow steppe combined with larch and birch forest 26. Grass steppe 27. Grass–sagebrush steppe Žsemidesert. 28. Sagebrush and salt bush desert 29. Psammophytic desert with Haloxylon and psammophillous bushes 30. High mountain woodlands, tundra-like and meadow plant formations 31. Semisavanna 32. Mountain grass communities combined with xerophillous bushes 33. Kamchatka birch woodland Total
629 342 223 506 1511 1285 205 311 813 1304 70 1681 1209 703 798 256 104
2.0 4.4 7.1 7 16.7 28 23.4 34.0 22.6 21.5 15.1 13.2 24.2 20.5 28.1 31.4 20.5
1.3 1.5 1.6 3.5 25.2 36.0 4.8 10.6 18.4 28.0 1.0 22.2 29.3 14.4 224 8.0 2.1
0.59 0.68 0.72 1.57 11.34 16.20 2.16 4.77 8.28 12.60 0.45 9.99 13.19 6.48 10.08 3.60 0.95
720 307 2048 163 941 1023 498 53 392 729 496 591 795 143 55 96 –
23.1 20.2 35.0 23.6 13.0 9.6 7.2 7.2 1.3 0.7 6.7 19.6 5.4 3.5 1.3 11.2 –
16.6 6.2 71.7 3.8 12.2 9.8 3.6 0.4 0.45 0.5 3.3 11.6 4.3 0.7 0.1 1.1 377.1
7.47 2.79 32.27 1.71 5.49 4.41 1.62 0.18 0.20 0.22 1.49 5.22 1.94 0.32 0.05 0.50 169.7
155% of the modern Žpotential. phytomass and carbon storage.
BP. reached 105 Gt, that is, 122% of the phytomass storage in the modern potential vegetation Ž85.9 Gt..
References Adams, J.M., Faure, H., Faure-Denard, L., McGlade, J.M., Woodward, F.I., 1990. Increases in terrestrial carbon storage from the Last Glacial Maximum to the present. Nature 348, 711– 714.
Ajtay, G.L., Ketner, P., Duvigneaud, P., 1979. Terrestrial primary production and phytomass. In: Bolin, B., Degens, E.T., Kempe, S., Ketner, P. ŽEds.., The Global Carbon Cycle. SCOPE 13, Wiley, Chichester, pp. 123–181. Alekhin, V.V., 1951. Rastitel’nost’ SSSR. Sovetskaya Nauka, Moscow, 512 pp. Žin Russian.. Bazilevich, N.I., 1993. Biologicheskaya productivnost’ ecosistem Severnoi Evrazii. Nauka, Moscow, 293 pp. Žin Russian.. Gliemeroth, A.-K., 1995. Palaookologische Untersuchungen uber ¨ die letzten 22000 Jahre in Europa. Gustav Fischer Verlag, Stuttgart, 252 pp.
204
A.A. Velichko et al.r Chemical Geology 159 (1999) 191–204
Grichuk, V.P., 1979. Metodika interpretatsii paleobotanicheskikh materialov dlya resheniya zadach stratigrafii i korrelyatsii pozdnego kainozoya. In: Grichuk, V.P. ŽEd.., Palinologicheskiye issledovaniya na severo-vostoke SSSR. Akademiya Nauk SSSR, Dal’nevostochny Nauchny Tsentr, Vladivostok, pp. 5–22 Žin Russian.. Kuminova, A.V., 1960. Rastitel’nyi pokrov Altaya. Izdatel’stvo AN SSSR. Sibirskoye Otdelenie. Novosibirsk, 450 pp. Žin Russian.. Monserud, R.A., Denissenko, O.V., Kolchugina, T.P., Tchebakova, N.M., 1995. Global Biogeochemical Cycles 9 Ž2., 213–226. Rastitel’nost’ Evropeiskoi chasti SSSR, 1980. In: Gribov, S.A., Isachenko, T.I., Lavrenko, E.M. ŽEds.., Nauka, Leningradskoye otdelenie, Leningrad, 429 pp. Žin Russian..
Sochava, V.B., et al., 1964. Fiziko-geograficheskiy atlas mira, 1964. Akademiya Nauk SSSR i Glavnoye Upravleniye Geodezii i Kartografii GGK. SSSR, Moscow, pp. 280–288 Žin Russian.. Velichko, A.A. ŽEd.., 1984. Late Quaternary environments of the Soviet Union, University of Minnesota Press, Minneapolis, 327 pp. Velichko, A.A., ŽEd.., in print. Razvitiye landshaftov i klimata territorii Severnoi Evrazii. Atlas-monografiya, tom 2 Žin Russian.. Zelikson, E.M., Borisova, O.K., Kremenetsky, C.V., Velichko, A.A., 1998. Phytomass and carbon storage during the Eemian optimum, Late Weichselian maximum and Holocene optimum in Eastern Europe. Global and Planetary Change 16–17, pp. 181–195.